JP2005036882A - Double poppet type valve device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a double poppet type valve device improved in sealing property and preventing leakage effectively with its simple structure. <P>SOLUTION: This double poppet type valve device 10 is constituted by attaching two valves 34a, 34b to upper and lower parts of a valve shaft 22 and seating on two corresponding valve seats 36a, 36b formed in a valve body 14, respectively. A coating material 40 is applied to either of seating faces 34a1, 34b1 of two valves and two valve seats 36a, 36b corresponding to them, and the coating material is crushed by pressure even if a clearance exists between the valve and the valve seat to seal it. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a double poppet valve device.

The double poppet type valve is configured so that two valves are mounted on the upper and lower sides of the valve shaft and seated on two corresponding valve seats formed on the valve body, respectively. Since this type of valve has two valves on the top and bottom, the force balances even if differential pressure acts on the front and back of the valve, so the valve will not open even if the valve diameter is increased in order to ensure the flow rate. Can be. Therefore, it is often used for EGR valves. Examples thereof include the techniques described in Patent Documents 1 and 2.
JP-A-11-182355 International Publication No. W099 / 61775

  Incidentally, the double poppet type valve described above has a problem that one of the upper and lower valves cannot be closed due to variations in processing accuracy. Similar problems can occur when used as an EGR valve when the valve (and valve shaft) and valve seat materials are different and the linear expansion coefficients are different, or when there is a temperature difference between them.

  In this regard, in the technique described in Patent Document 1, in the state where one of the upper and lower valves is seated on the corresponding valve seat, the other valve and the corresponding valve seat A clearance is provided between the two, so that leakage of EGR gas during high-temperature thermal expansion is suppressed. However, this configuration has a disadvantage that it cannot prevent the leakage of EGR gas on the low temperature side.

  Moreover, in the technique of patent document 2, it is comprised so that a sealing performance may be improved by mechanically deforming a valve or a valve seat. According to this proposed technique, the leakage of EGR gas can be suppressed regardless of the ambient temperature, but there is a disadvantage that the structure of the valve and the valve seat becomes complicated.

  Accordingly, an object of the present invention is to provide a double poppet type valve device which solves the above-mentioned problems and has a simple structure but improves sealing performance and effectively prevents leakage.

  In order to solve the above-mentioned object, according to claim 1, two valves are attached on the upper side close to the actuator of the valve shaft and on the lower side separated from the actuator, and two corresponding valves formed on the valve body. In the double poppet type valve device to be seated on each of the seats, at least one of the four locations comprising the seating surfaces of the upper and lower two valves and the corresponding two valve seats The coating material was applied to the film.

  According to a second aspect of the present invention, the coating material is applied at at least two locations on the upper and lower sides, and the coating thickness is made different between the upper and lower sides.

  In the double poppet type valve device according to claim 1, the coating material is applied to at least one of the four locations including the seating surfaces of the upper and lower two valves and the two valve seats corresponding thereto. Since it is configured to be applied, with one of the two upper and lower valves seated on the corresponding valve seat due to variations in processing accuracy, differences in the linear expansion coefficient of the material, or temperature differences, Even if there is a clearance between the other valve and the corresponding valve seat, the upper and lower two valves move while crushing the coating material toward the valve seat, so seal with the crushed coating material. can do. Therefore, although it is a simple structure, a sealing performance can be improved and a leak can be prevented effectively.

Therefore, even when used as an EGR valve, leakage of EGR gas can be effectively prevented by improving the sealing performance. In that case, if an EGR gas component contains an adhesive substance, it may adhere to the valve seat and cause sticking of the valve (defective valve opening), but a non-adhesive material is used as the coating material. By doing so, such inconvenience can be solved to some extent. For example, when molybdenum disulfide (MoS ₂ ) is used as a coating material, the water repellency is high, so that such substances can be prevented from adhering to some extent and the heat resistance is relatively high. There is an advantage that is hard to damage.

  In the above description, “applying the coating material to at least one of the four locations consisting of the seating surfaces of the upper and lower two valves and the two valve seats corresponding thereto” means that the coating material is When applying only to the seating surfaces of the upper and lower two valves (two locations), when applying only to the upper and lower two valve seats (two locations), both the upper and lower valve seating surfaces and the valve seat (4 locations) When applied, and applied to one of the upper valve seating surface and valve seat (for example, the valve seating surface), and to the other lower valve seating surface and valve seat (for example, the valve seat) (2 places) In the case of application, it includes any of the cases where the application is applied to only one of the seating surfaces of the upper and lower valves and the valve seat, for example, only the seating surface of the lower valve.

  In the double poppet type valve device according to the second aspect, the coating material is applied at at least two places on the upper and lower sides, and the coating thickness is made to be different between the upper and lower sides. That is, in the case of a double poppet type valve, since there are two seat portions at the top and bottom, either the top or bottom sealability must be sacrificed due to the limit of processing accuracy. In that case, by giving priority to the sealing performance of the valve on the upper side, that is, on the side close to the actuator that drives the valve, and by managing the dimensions so as to sacrifice that of the valve on the lower side, that is, on the side away from the actuator. In addition, the influence of the leaked gas on the actuator can be suppressed. This is particularly beneficial when used as an EGR valve because the gas is a hot EGR gas.

  In this case, however, the clearance at the lower valve must be allowed. In that case, the coating thickness of the coating material is made different between the upper and lower sides, more specifically, the coating thickness of the coating material of the lower valve is made thicker than that of the upper side. Therefore, the sealing performance of the lower valve can be further ensured.

  The best mode of a double poppet valve device according to the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is an explanatory sectional view generally showing a double poppet type valve device according to a first embodiment of the present invention, and FIG. 2 is an explanatory view schematically showing it.

  In FIG. 1, reference numeral 10 denotes a double poppet type valve device. An example of the valve device is an EGR valve device. A double poppet type valve device (hereinafter referred to as “EGR valve device”) 10 is inserted in an EGR passage (shown by an imaginary line 12) for returning exhaust gas of an internal combustion engine (not shown) to an intake system (not shown). A valve body 14 and an actuator unit 20 connected to the valve body 14 by bolts 16 are also included.

  A valve shaft 22 is accommodated inside the valve body 14 and the actuator portion 20 so as to penetrate them. The distal end side (upper side in the drawing) of the valve shaft 22 is fixed to the member 24 having a substantially H shape in cross section in the actuator portion 20 with a slight gap 24a and screwed (not shown). An electromagnetic solenoid (actuator) 26 is disposed in the vicinity of the member 24. The electromagnetic solenoid 26 includes a coil 26a and a magnetic body 26b disposed around the coil 26a.

  The electromagnetic solenoid 26 is connected to a power source (not shown) and is excited when energized to drive (pull) the member 24 (and the valve shaft 22 screwed to the member 24) in the axial direction, more specifically, downward in FIG. . A return spring (compression spring) 30 is mounted in the gap formed in the lower part of the member 24, and the member 24 (and the valve shaft 22 screwed to the member 24) is opposed to the axial direction, more specifically, FIG. Is biased upward. Reference numeral 32 denotes a bearing portion, and 32a denotes a sealing material.

  Two valves 34 a and 34 b are attached to the valve shaft 22 on the upper side close to the electromagnetic solenoid (actuator) 26 and on the lower side separated from the upper side. On the other hand, the valve body 14 is formed with two valve seats 36a and 36b corresponding to the valves 34a and 34b. Seating surfaces 34a1 and 34b1 are formed on the two valves 34a and 34b (shown well in FIG. 2).

  When the valve shaft 22 is driven in the axial direction (downward in the figure) by the excitation of the electromagnetic solenoid 26, the two valves 34a and 34b are both opened away from the valve seats 36a and 36b. As a result, as shown by the arrows in FIG. 1, the exhaust gas (EGR gas) that flows in flows out through the two valves 34a and 34b. When the electromagnetic solenoid 26 is demagnetized, the valve shaft 22 is driven in the opposite direction by the urging force of the return spring 30, and the two valves 34 a and 34 b are both seated on the valve seats 36 a and 36 b and pass through the EGR passage 12. Close.

  The EGR valve device 10 is thus composed of a double poppet type valve, is inserted into an EGR passage 12 that recirculates exhaust gas of the internal combustion engine to the intake system, is connected to an electromagnetic solenoid (actuator) 26, and is also electromagnetically connected to the valve shaft 22. Two valves 34a and 34b are attached to the upper side close to the solenoid 26 and the lower side away from the solenoid 26, and are seated on the corresponding two valve seats 36a and 36b formed in the valve body 14 to close the EGR passage 12. Configured to do.

  The valve shaft 22 and the valves 34a and 34b are made of a stainless material. The valve seats 36a and 36b are also made of a stainless material and are made separately from the valve body, and are fitted into the valve body 14 by an appropriate method.

  At least one of the four locations including the seating surfaces 34a1 and 34b1 of the two upper and lower valves 34a and 34b and the two valve seats 36a and 36b corresponding thereto, more specifically, the seating surface. A coating material 40 is applied to 34a1 and 34b1 (for convenience of understanding, the coating material 40 is exaggerated in FIG. 1).

  As described above, since the double poppet type valve device balances the force even if a differential pressure acts on the front and back of the valve, the valve diameter can be increased to secure the flow rate. However, there is a problem that one of the upper and lower valves 34a and 34b cannot be closed due to variations in processing accuracy. Similar problems may occur when the materials of the valve 34 (and the valve shaft 22) and the valve seat 36 are different and the linear expansion coefficients are different, or when there is a temperature difference between them.

  Therefore, in the EGR valve device according to this embodiment, the coating material 40 is applied to the seating surfaces 34a1 and 34b1 of the two upper and lower valves 34a and 34b. As a result, one of the two upper and lower valves 34a, 34b is seated on the corresponding valve seat due to variations in processing accuracy, a difference in the linear expansion coefficient of the material, or a temperature difference. Even if there is a clearance between the valve and the corresponding valve seat, the upper and lower two valves 34a and 34b move while collapsing the coating material 40 toward the valve seats 36a and 36b. It is possible to seal with the applied coating material 40. Therefore, while having a simple structure, the sealing performance can be improved and the leakage of EGR gas (exhaust gas) can be effectively prevented.

  In terms of this variation in machining accuracy, in the case of a double poppet type valve, as shown in FIG. 2, there are two seat portions 42 at the top and bottom. Such sealing performance must be sacrificed. Therefore, in this embodiment, priority is given to the sealing property of the valve 34a on the upper side, that is, the side close to the electromagnetic solenoid (actuator) 26 that drives the valve, and the lower side, that is, the side separated from the electromagnetic solenoid 26. It was decided to perform dimensional control so as to sacrifice that of the valve 34b.

  Thereby, it is possible to suppress the influence of the leaked EGR gas on the electromagnetic solenoid 26, that is, the heat damage of the EGR gas or the intrusion of the leaked EGR gas into the electromagnetic solenoid 26. In this case, however, the clearance at the lower valve 34b must be allowed, so that the coating material 40 is applied to the seating surfaces 34a1 and 34b1 of the upper and lower valves 34a and 34b as described above. I did it.

  Further, the coating material 40 is applied at at least two locations on the upper and lower sides, and the coating thickness is made to be different between the upper and lower sides. It was configured to be thicker than that of (34a1). More precisely, the coating thickness of the coating material 40 on the seating surface 34b1 of the lower valve 34b is set to 30 μm, for example, while that on the upper side (34a1) is set to 10 μm and the lower coating thickness is set to that on the upper side. It was configured to be thicker than that. Thereby, the sealing performance at the lower valve 34b can be further ensured.

Further, when the EGR gas component contains an adhesive substance, it may adhere to the valve seats 36a and 36b and cause sticking of the valve (defective opening), but the coating material 40 has non-adhesiveness. By adopting the material, such inconvenience can be solved to some extent. For example, when molybdenum disulfide (MoS ₂ ) is used as a coating material, the water repellency is high, so that such substances can be prevented from adhering to some extent, and the heat resistance is relatively high. There is an advantage that it is difficult to melt.

  When molybdenum disulfide is used as the coating material, specifically, an appropriate solvent is added to the molybdenum disulfide crystal and applied in a liquid state.

  Molybdenum disulfide is an example, and any material may be used as long as it is excellent in water repellency (or non-adhesiveness) and heat resistance. For example, Teflon (registered trademark), fluorine, Graphite is also conceivable.

  In the above description, “the coating material is applied to at least one of the four locations including the seating surfaces of the upper and lower two valves and the corresponding two valve seats” means the coating material 40. Is applied only to the seating surfaces 34a1 and 34b1 of the upper and lower two valves (two places), and is applied only to the upper and lower two valve seats 36a and 36b (two places), the upper and lower two valves When both are applied to the seating surfaces 34a1, 34b1 and the valve seats 36a, 36b (four locations), and applied to one of the seating surface 34a1 of the upper valve 34a and the valve seat 36a (for example, the valve seating surface 34a1), When applying (two places) to the seating surface 34b1 of the side valve 34b and the other (for example, the valve seat 36b) of the valve seat 36b, Lube seating surface 34a1,34b1 and the valve seat 36a, any of a 36b, for example, may be either in the case of applying to one place only seating surface 34b1 of the lower side of the valve.

  Since this embodiment is configured as described above, in the double poppet type valve device, it is possible to improve the sealing property and effectively prevent the leakage of EGR gas (exhaust gas) while having a simple structure. .

  As described above, in the first embodiment of the present invention, the two valves 34a, which are connected to the actuator (electromagnetic solenoid) 26, on the upper side close to the actuator of the valve shaft 22 and on the lower side away from the actuator, are provided. In the double poppet type valve device attached to 34b and seated on the corresponding two valve seats 36a, 36b formed on the valve body 14, seating surfaces 34a1, 34b1 of the upper and lower two valves The coating material 40 is applied to at least one of the four valve seats 36a and 36b corresponding thereto.

  In addition, the coating material 40 was applied at at least two locations on the top and bottom, and the coating thickness was made to be different between the top and bottom.

  In the above-described embodiment, the EGR valve has been described as an example. However, the present invention is not limited to this, and any valve can be applied as long as it is a double poppet valve.

BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory sectional drawing which shows the double poppet type valve apparatus based on 1st Example of this invention generally. Similarly, it is explanatory drawing which shows typically the double poppet type valve apparatus which concerns on 1st Example.

Explanation of symbols

10 Double poppet type valve device (EGR valve device)
12 EGR passage 14 Valve body 20 Actuator part 22 Valve shaft 26 Electromagnetic solenoid (actuator)
34a, 34b Valve 34a1, 34b1 Seating surface 36a, 36b Valve seat 40 Coating material

Claims (2)

  In the double poppet type valve device in which two valves are attached to the upper side close to the actuator of the valve shaft and the lower side away from the actuator, and are respectively seated on the corresponding two valve seats formed on the valve body. 2. A double poppet type valve device, wherein a coating material is applied to at least one of four places comprising the seating surfaces of the two upper and lower valves and the two valve seats corresponding to the seating surfaces. 2. The double poppet valve device according to claim 1, wherein the coating material is applied at at least two locations on the upper and lower sides, and the coating thicknesses are made different between the upper and lower sides.

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